Mega Man 9

Below is the suggested order to defeat the Robot Masters in, as well as which weapons to use on both them and the bosses in Dr. Wilyís castle. Keep in mind that in terms of the Robot Masters, you can jump in at any point, but we recommend beginning with Galaxy Man and going from there.

Galaxy Man - Use Mega Buster

Jewel Man - Use Black Hole Bomb

Plug Man - Use Jewel Satellite

Tornado Man - Use Plug Ball

Magma Man - Use Tornado Blow

Hornet Man - Use Magma Bazooka

Splash Woman - Use Hornet Chaser

Concrete Man - Use Laser Trident

Wall Shooters - Use Mega Buster

Giant Machine - Use Laser Trident*

Blob Monster - Use Black Hole Bomb

Dr. Wily #1 - Use Mega Buster

Dr. Wily #2 - Use Mega Buster

Dr. Wily #3 - Use Plug Ball**

* - The Laser Trident is the weakness of all 3 sections of this boss, but the middle section is made much, much easier by using the Tornado Blow on it.

** - The Plug Ball is the primary weakness of Wily's final form (the UFO). However, if he appears too high to attack with the Plug Ball, quickly switch over to the Hornet Chaser and use it on him. They will hit him high above for only one bar of energy per strike, but it will help you decrease his energy a little bit more.

How to: Go back to Plug Manís stage after clearing it. By playing through the stage over again in its entirety, you can collect 2 more extra lives, an E-Tank (the only E-Tank in any of the 8 Robot Master stages) and about 45 screws per visit. It is indeed the most lucrative of the stages to head to in this regard.

The Jewel Satellite on just about every stage will allow you to easily harvest screws and extra lives from unsuspecting enemies as well. The best place to use the Jewel Satellite is in the initial run on Concrete Manís stage. The birds, the rocks they drop, and the enemies that come out of holes in an attempt to knock you into them will give you endless amounts of screws and extra lives if enough time is spent. Run back and forth with the Jewel Satellite equipped during on the 1st section of Concrete Manís stage, respawning enemies and collecting ridiculous amounts of screws!

There is another great trick to get as many screws as you need. With the Jewel Satellite in your inventory, head to Plug Manís stage. Head to the 1st pipe you find that spawns endless amounts of slow-moving floating robots. Engage the shield and sit right next to the pipe. Enemies will run into you from above, dropping whatever items they drop right on top of you, including small screws. Stand there for as long as needed to acquire the amount of screws you want.

The above technique described by bergsandwich is an awesome one. Keep in mind that with the Jewel Satellite engaged at the proper areas on Plug Man's stage, you can actually walk away from your game for as long as needed as enemies funnel towards you, dropping items right on top of Mega Man. So, if you need to farm, you can do so while you do something else entirely!

Another great place to farm for screws and extra lives is on Hornet Manís stage. Head to the area near the beginning of the stage with 2 missile-launching flower pots. Stand on the 2nd of the 3 steps heading left and use the Jewel Satellite to destroy their flower missiles. Positioning yourself in such a way that destroyed missiles drop items right on Mega Man, you can stand here indefinitely and farm screws and lives at your leisure. Try it!

How to: Equip the Hornet Chaser. The Hornet Chaser, when deployed, will attack and damage the rock foe even when heís on the ceiling, forcing him to come down where you can quickly finish him off.
To easily defeat the flame dragon miniboss on Magma Manís stage and in Dr. Wilyís castle, consider equipping the Concrete Shot. Five shots to the face of the dragon with the Concrete Shot will quickly dispatch it. While the Black Hole Bomb will suck all of the flames off of the dragonís body, rendering it unable to attack, it wonít heavily damage the dragon itself. Use the Concrete Shot instead.

Want to farm for screws and the like? Then consider going back to Plug Manís stage after clearing it. By playing through the stage over and over again in its entirety, you can collect per visit:
2 extra lives
an E-Tank (the only E-Tank in any of the 8 Robot Master stages)
around 45 screws

It is indeed the most lucrative of the stages to head to in this regard.

The Jewel Satellite on just about any stage will allow you to easily harvest screws and extra lives from unsuspecting enemies as well. The best place to use the Jewel Satellite is in the initial run on Concrete Manís stage. The birds, the rocks they drop, and the enemies that come out of holes in an attempt to knock you into them will give you endless amounts of screws and extra lives if enough time is spent. Run back and forth with the Jewel Satellite equipped during on the 1st section of Concrete Manís stage, respawning enemies and collecting ridiculous amounts of screws!

There is another great technique to get as many screws as you need. With the Jewel Satellite in your inventory, head to Plug Manís stage. Head to the 1st pipe you find that spawns endless amounts of slow-moving floating robots. Engage the shield and sit right next to the pipe. Enemies will run into you from above, dropping whatever items they drop right on top of you, including small screws. Stand there for as long as needed to acquire the amount of screws you want.

The above technique described by bergsandwich is an awesome one. Keep in mind that with the Jewel Satellite engaged at the proper areas on Plug Man's stage, you can actually walk away from your game for as long as needed as enemies funnel towards you, dropping items right on top of Mega Man. So, if you need to farm, you can do so while you do something else entirely!

The Rush Jet Adaptor is acquired differently in Mega Man 9 than you may be accustom to. Instead of getting it when defeating a specific Robot Master and assimilating the skill along with that Robot Masterís weapon, the Rush Jet Adaptor is earned by Mega Man after any 5 Robot Masters are slain. When the fifth is killed, Roll and Auto will automatically give Mega Man this adaptor.

Mega Man 9 is hard. There are 2 specific items that will help you beyond the usual batch of extra lives and E-Tanks that you should consider purchasing with your screws if you are having difficulty. The 1st item to be considered are Shock Guards, which can be purchased from Auto and Roll and will allow you to survive any unintentional encounter with instant-kill spikes (once per purchase). The other item is called a Beat Call, and will automatically save you from any unintentional encounter with a pit or chasm (once per purchase). If you are having difficulty getting through any given stage, especially in Dr. Wilyís castle, consider a visit to the store to purchase these 2 items to even the odds.